I read this Wikipedia article, and it said that Omamori are often said to derive their power from NOT being opened, so I guess I'm surprised that SGI gives out Omamori and encourages people to open them. https://en.wikipedia.org/wiki/Omamori

Also, I was wondering if anyone knows why the SGI Omamori is so prone to cracking. I wonder why they didn't decide on a more durable material.

I know a few SGI folks with omamori gohonzon, I've not heard them proposed to be any different than a regular gohzonzon- just portable, OTOH other schools may view them differently. In SGI around here they are inserted in a small butsudan, which is opened for the gongyo/daimoku. Its sort of a theoretical exercise when looking at one across a room, but better than chanting to a wall with eyes closed. My district chief has one he brings to meetings at member's houses who have not yet received gohonzon. Some folks carry them on travel for chanting etc in hotel rooms. Back in the old NSA days I participated in some of the parade activities in preparation for which an entire auditorium of folks did gongyo & daimoku to an omamori placed on a table on-stage.

It was an interesting experience- the setup was a school auditorium from which we took buses to the event; the school being a convenient place to gather. OTOH the stage was empty except for the table which was arranged as an impromptu altar, I don't recall incense, candles etc- though the gohonon itself was too small to be viewed it was possible to focus on it as an object. This is one of the aspects of NSA and still in SGI that I like; its considered perfectly reasonable to assemble a DIY altar and do gongyo pretty much anywhere or anytime, anything practicable from cardboard boxes on up, or even a nearby rock is fine. Temporarily enshrining a paper gohonzon for such a purpose wouldn't be recommended though.

Which does lead me to wonder whats the most irregular place I've ever done gongyo; off the top of my head, on the dirt floor of a barn, illuminated by a campfire. For a few summers I had a more formal altar built of scrap lumber in a bunkhouse in backwoods Maine.

Check out Kanse Kapon's study of Gohonzon. There are arguments to be made that Nichiren inscribed at least some Gohonzon as personal omamori to be carried around, not necessarily enshrined. Or, at least, some people carried them around that way.

Just to point out - most omamori are supposed to be exchanged after a year. This is not the case with omamori Gohonzon.

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"At one time, President Ikeda was living in an out of the way prefecture and when he moved, he left his omamori Gohonzon behind. You would have thought the statue of the Virgin Mary was crying tears of blood the way people flooded there to chant to it. The number of people who made a pilgrimage there far outnumbered those who went to see the Daigohonzon that year."